v2.4.1

Updates:

• Prefix local action bash variable names with PUSH_PROTECTED_ to avoid clashing with workflow bash variables (#51)
• Update action.yml default values to explicitly be variables (#51)

Developer updates:

• Update dependencies (#49)
  • pre-commit~=2.15
• Update pre-commit hook black to v21.9b0.
• Silence HTML code linting in README.md.